rm (while in processor thread 0) in error message?

[youngsofun]

some tests expect exact error message

while the number 0 may change for each run.

cc @zhang2014

[Xuanwo]

Can we check error code?

[youngsofun]

1. sometimes we want to give a pretty error message, like SQL syntax error, which point out where is the error, what I encounter is format error, although not need to be as pretty as sql syntax error.
2. the are error like the sql syntax error or format can not have an error code for each case

currently I use | grep -c 'somekeyword' or | head -c N to work around